Questions about sorting

Now there is a classification table that contains the following fields

• Id
• ParentID Parent ID
• Orders the order in which the item is displayed at its level, the smaller the value, the lower the previous
• Text content

For example, such as the following data (text field content is only to facilitate the description of the writing, the actual content is not so):

ID	ParentID	Order	text
1	0	10	1
2	0	0	2
3	1	20	1-2
4	1	10	1-1
5	3	20	1-2-2
6	3	10	1-2-1
7	2	30	2-1

How to sort it (roughly sorted by ParentID and order)

ID	ParentID	Order	text
2	0	0	2
7	2	30	2-1
1	0	10	1
4	1	10	1-1
3	1	20	1-2
6	3	10	1-2-1
5	3	20	1-2-2

In simple terms, it is an infinite classification of sub-categorical sorting problems. Sort by parent-child category first, and then sort all sibling categories by order.

I am using the most stupid method, is to separate each layer of classification read out (recursive), sorted into the total number of groups, and currently only tested on the 3-level classification of support, but feel this efficiency is low ah, do not know what good algorithm, hope God help, or pointing twos, do a good job based on PHP.

Reply content:

Now there is a classification table that contains the following fields

• Id
• ParentID Parent ID
• Orders the order in which the item is displayed at its level, the smaller the value, the lower the previous
• Text content

For example, such as the following data (text field content is only to facilitate the description of the writing, the actual content is not so):

ID	ParentID	Order	text
1	0	10	1
2	0	0	2
3	1	20	1-2
4	1	10	1-1
5	3	20	1-2-2
6	3	10	1-2-1
7	2	30	2-1

How to sort it (roughly sorted by ParentID and order)

ID	ParentID	Order	text
2	0	0	2
7	2	30	2-1
1	0	10	1
4	1	10	1-1
3	1	20	1-2
6	3	10	1-2-1
5	3	20	1-2-2

In simple terms, it is an infinite classification of sub-categorical sorting problems. Sort by parent-child category first, and then sort all sibling categories by order.

I am using the most stupid method, is to separate each layer of classification read out (recursive), sorted into the total number of groups, and currently only tested on the 3-level classification of support, but feel this efficiency is low ah, do not know what good algorithm, hope God help, or pointing twos, do a good job based on PHP.

Data structure: Sets a virtual parent category for all top-level classifications, and then each cluster has a reference to its ordered subcategory array.
Sort operation: Performs an operation on each node that gets all the subcategories and then saves them to an array.

If you have to put it in the same array, then put the results in the same order after the sorting is done.
Of course, I recommend modifying the method of reading an array so that it can parse the tree structure.

I have a train of thought. When retrieving data from a database, order by parentid ASC, order ASC, according to ParentID and order

Get all the data in a loop into PHP:
foreach ($list as $v) {
$tmp [$v [' parentid ']][] = $v;
}
This is a well-ordered, root node with a subset
One more recursive, add the root node to the line.

Query, all queries out, only to order sort

Iterate through the constructed array at once

$data = array();foreach ($rows as $r) {    $data['item'][$r['id']] = $r;    $data['parent'][$r['id']] = $r['pid'];    $data['children'][$r['pid']][] = $r['id'];}

Use the general traversal data['children'][当前需要遍历的父ID] , and then by data['item'][当前ID] finding the specified entry

Not to meet the squirt

